1. Field of the Invention
The present invention relates to an improvement in a camera having a cartridge chamber lid for shielding a cartridge chamber from light.
2. Description of Related Art
In recent years, film cartridges of the types which are provided with light-lock doors (light-shielding doors) have been proposed. For example, the film cartridge disclosed in U.S. Pat. No. 5,347,334 belongs to these types. This kind of film cartridge is a so-called thrust type of film cartridge. If the film cartridge is not loaded in a camera, its film is wound in the film cartridge with its leader portion being accommodated therein, and if the film cartridge is loaded in the camera, the film is fed out of the film cartridge by a film transporting mechanism of the camera and is wound around a take-up spool of the camera.
In the camera which uses the thrust type of film cartridge, since the film cartridge can be loaded into or unloaded from the film cartridge in the axial direction of the take-up spool, the film cartridge can be made comparatively small and the cartridge chamber lid can be provided at the top or bottom of the body of the camera.
After the film cartridge is loaded into this type of camera, if the cartridge chamber lid accidentally opens while the film is being wound, a silver-halide film may be exposed. If a user attempts to open the cartridge chamber lid and forcedly take out the film cartridge with the film being pulled out of the film cartridge, not only will the film be exposed but also the film will be broken, and broken pieces of the film will be left in the camera. In this case, because of the smallness of the cartridge chamber lid, the user will find it difficult to remove the broken pieces, and the camera may need repair.
To prevent the occurrence of the above-described problems, it is preferable that the cartridge chamber lid be arranged not to open accidentally. Since the camera which uses the thrust type of film cartridge has the above-described problems, it is desired that the cartridge chamber lid be arranged not to open accidentally.
To this end, several methods have heretofore been proposed with respect to the camera using such a film cartridge, for the purpose of preventing the cartridge chamber lid from being erroneously opened when the film is pulled out.
For example, there is a method which, if a film may be exposed to light when a cartridge chamber lid is opened, prevents accidental opening of a cartridge chamber lid by engaging the cartridge chamber lid or an engagement member thereof with a lock member by using the movement of a magnetic actuator or that of a dedicated motor.
As another example, a method of disabling manipulation of a cartridge chamber lid opening/closing switch only when a film is wound up is disclosed in Japanese Laid-Open Patent Application No. Sho 63-25634. According to this method, a rewinding switch and the cartridge chamber lid opening/closing switch are provided in close proximity to each other on a camera body so that the cartridge chamber lid opening/closing switch is difficult to press, so long as the rewinding switch is not depressed.
However, in the above-described method of locking the cartridge chamber lid so that the cartridge chamber lid is not erroneously opened if the film loaded in the camera may be exposed to light when the cartridge chamber lid is opened, there is a need for an electrical or magnetic dedicated actuator for moving the lock member, thus resulting in the disadvantages that costs increase, that extra electrical energy is consumed to operate the actuator, and that a space into which to incorporate the actuator must be provided in the camera.
In the method for the camera proposed in Japanese Laid-Open Patent Application No. Sho 63-25634, which method, so long as the rewinding switch is not depressed, does not allow the cartridge chamber lid opening/closing switch to be easily pressed, the rewinding switch must be provided in close proximity to the cartridge chamber lid opening/closing switch, so that the design of the exterior appearance of the camera is restricted. Otherwise, because of a structure which merely does not allow the cartridge chamber lid opening/closing switch to be easily pressed, the cartridge chamber lid may be opened by the friction between a finger tip and the surface of the cartridge chamber lid opening/closing switch, or reliability similar to the reliability of a conventional camera of the type in which a rewinding switch is not provided in proximity to a cartridge chamber lid can only be obtained at the time of a vibration, falling or the like of the camera. Furthermore, the construction in which the cartridge chamber lid opening/closing switch and the rewinding switch must be provided near to each other may allow the user of the camera to unconsciously manipulate the rewind switch, and may also make it difficult for the user to perform the manipulation of opening or closing the cartridge chamber lid.
In the camera proposed in Japanese Laid-Open Patent Application No. Hei 7-319057, if a lock member which is elastically urged in frictional contact with a transmission gear of a film winding gear train is rotated in the film winding direction, the lock member can be turned to engage a manipulating member for opening or closing a cartridge chamber. However, if the transmission gear rotates in the opposite direction during film rewinding, the lock member turns to release the engagement of the manipulating member, and becomes unable to prevent accidental opening or closing of the cartridge chamber lid in the course of film rewinding.